Researchers have successfully printed two-dimensional materials such as graphene (a single layer of carbon in a hexagonal lattice), directly onto textiles, enabling the production of wearable integrated electronic circuits. The inkjet printing process used was based on standard techniques which helps keep the production of these new fabric-based electronic devices sustainable, low-cost and scalable.
Perfecting the 2D material printing
The researchers outline in a paper published in the journal Nature Communicationshow they designed low-boiling point, non-toxic inks, which were directly printed onto polyester textile. This process demonstrated viability for wearable printed integrated circuits which can function at room temperature and pressure. Crucially, with this new approach the researchers were able to surpass the conventional process which creates singular transistors, as they were able to print whole integrated electronic circuits.
The team discovered that the roughness of textiles influenced the electrical properties of the electronics and that smoothing the surface of the textiles, using a so-called ‘planarisation layer’, meant they were able to improve the performance of the printed devices.
One of the main advantages that the technique has over alternatives, is its versatility. The majority of current wearable electronic devices are created from relatively rigid components which are then mounted on wearable materials such such as textiles, plastic or rubber. However, these are often impractical as they can be uncomfortable to wear allowing limited accommodation for the human body, they are not breathable for example. They can also be easily damaged during washing. The team’s product is both comfortable to wear and able to withstand up to 20 washing cycles in a standard machine.
According to Dr Felice Torrisi of the Cambridge Graphene Centre, the paper’s senior author, another advantage of the team’s technique is that as he told EurekAlert, ‘Other inks for printed electronics normally require toxic solvents and are not suitable to be worn, whereas our inks are both cheap, safe and environmentally-friendly, and can be combined to create electronic circuits by simply printing different two-dimensional materials on the fabric.’
The team took advantage of the fact that graphene and hexagonal-boron nitride are atomically thin 2D materials and so can be flexibly arranged into structures displaying novel properties, beyond those of their individual components. This means that the conducting, insulating and semiconducting properties of the 2D materials can be harnessed to facilitate the specific performance required.
Scalable for complexity and performance
There are a wide range of potential commercial applications for the technology from wearable devices that monitor personal health and well-being, to the augmentation of military capability. One field likely to take advantage of these developments, is that of the Internet of Things. As Dr Torrisi foresees, ‘Thanks to nanotechnology, in the future our clothes could incorporate these textile-based electronics, such as displays or sensors and become interactive.’
Using graphene and other related 2D materials inks to create electronic components and devices, which can be seamlessly integrated into fabrics, is at the forefront of efforts towards achieving smart textiles. Smart textiles themselves can be viewed as part of a wider effort to further blur the line between technology and everyday items, often referred to as ‘ubiquitous computing’.
The authors of the research paper are a part of the Graphene Flagship consortium, a pan-European, 10-year research and innovation initiative jointly funded by the EU, alongside member states and associated countries. It was established to support efforts that exploit the potential of graphene and related technologies, bringing applications to the marketplace.